Tobacco-smoke filters

ABSTRACT

The invention concerns an improved filter for tobacco smoke comprising fibrous, filamentary or sheet tobacco-smoke filtering material treated with a stable, involatile, free-radical containing substance selected from the group consisting of 9oxyl-bicyclo-(3,3,1)-nonan-3-one; 1-nitronyl-3-oxyl-4,4,5,5tetramethyl-2-phenyldihydroimidazole; and 1-oxyl-3-nitronyl-4,5phenanthro-2-methyldihydroimidazole.

United States Patent [54] TOBACCO-SMOKE FILTERS 2 Claims, No Drawings [52] U.S.Cl 131/267 [5 1 Int. Cl ..A24b 15/02, A24d 01/06 [50] Field of Search 131/2, 266, 17, 267, 268; 260/294.7, 309, 309.2

[56] References Cited UNITED STATES PATENTS 3,319,635 5/1967 Stahly 131/266 X 3,217,719 11/1965 Spears et a1 131/266 3,327,715 6/1967 Azorlosa 131/266 X 3,410,277 I H1968 Dalhamn 131/267 X OTHER REFERENCES Sax; N. 1. Dangerous Properties of Industrial Materials. Reinhold Book Corp., New York 1968. Pages 395, 486, 536, 779, 962 cited.

Primary Examiner-Samuel Koren Assistant Examiner-George M. Yahwak Anomey Kane, Dalsimer, Kane, Sullivan & Kurucz ABSTRACT: The invention concerns an improved filter for tobacco smoke comprising fibrous, filamentary or sheet tobacco-smoke filtering material treated with a stable, involatile, free-radical containing substance selected from the group consisting of 9-oxyl-bicyclo-(3,3,1)-nonan-3-0ne; 1- nitronyl-3-oxyl-4,4,5,S-tetramethyI-Z-phenyldihydroimidazole; and loxyl-3-nitr0nyl-4,5-phenanthro-2- methyldihydroimidazole.

TOBACCO-SMOKE FILTERS This invention concerns improvements relating to filters for tobacco smoke, particularly but not exclusively cigarette filters.

It is well known that the smoke from burning tobacco comprises a wide variety of different chemical substances which may be contained wholly in either the particulate phase or the vapor phase of the smoke, or partially in both. Many of the compounds which give tobacco smoke its characteristic and desireable flavor and aroma are contained in the vapor phase of the smoke. However, in order to improve the organoleptic properties of the smoke, particularly the flavor and aroma, it would be advantageous to remove certain components of the vapor phase of the smoke. Among these it may be particularly desired to remove substances which comprise a group of 1 atoms of such electronic constitution that at least one unpaired electron is present, especially nitric oxide and possibly other free radicals present in tobacco smoke.

An object of the present invention is to provide means whereby a substantial proportion of such a substance or substances, particularly nitric oxide, can be removed from tobacco smoke.

According to the invention, fibrous, filamentary or sheet tobacco-smoke filtering material is treated with a stable, involatile, free-radical containing substance of general formula RRNO. The free-radical character of the nitroxide is particu larly effective in removing nitric oxide from tobacco smoke. In general, the product of the reaction of the nitroxide with nitric oxide is a simple adduct:

RR'NO--NO RR'NO-N=O R and R are radicals whose nature may vary considerably and may be an alkyl, aromatic, alicyclic, heterocyclic or polycyclic group. These groups may contain functional groups such as, carbonyl, hydroxyl, amine, amide, nitrile, acyl, vinyl, nitrone, carboxyl, halogen, nitrosulphonyl and ether. The nitroxidel group itself may be part of a cyclic or polycyclic system.

Three nitroxides have been found to react effectively with nitric oxide:

a. 9-oxyl-bicyclo-(3,3,l )-nonan-3-one having the general formula:

b. l-nitronyl-3-oxyl-4,4,5,S-tetramethyl-Z-phenyldihyroimidazole having the general formula:

c. l-oxyl-3nitronyl-4,5-phenanthro-2-methyldihydroimidazle having the general formula:

The nitroxide may be applied to the filtering and supporting material, which constitutes the bulk of the filter, as a solid in powder form by dusting or as a liquid in solution or dispersion form by dipping or spraying. This may be done before or during the formation of the filter. The amount of the nitroxide, or a combination of nitroxides, added may be up to percent by weight of the original weight of the filtering and supporting material. Examples of preferred methods of carrying out the invention are as follows:

Example I Paper-filtering material was sprayed with an aqueous or alcoholic solution of 9-oxyl-bicyclo-(3,3,l )-nonan-3-one, so as to give a content of 10 percent by weight (referred to the original weight of the said material) of nitroxide after removal -of the solvent by drying. The treated paper was made into filter plugs of 15 mm. length. These were attached to cigarettes and smoked using a smoking engine which provided one puff per minute of two seconds duration and of 35 ml. volume. On analysis of the smoke from the cigarettes, it was found that between 45 and percent of nitric oxide was removed.

Example 2 The procedure was as in example l, but using an aqueous or (3 ,3,1 )-nonan-3-one: l-nitronyl-3-nitronyl-4,5-phenanthro-2- methyldroimidazole.

2. The filter of claim I wherein the said substance is sprayedonto the filtering material as a solution.

Patent No.

Inventor(s) At Col. 1, line 30,

At Col. 2, line 1,

line 2,

In the Claims:

Claim 1, line 48,

line 53,

line 54 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Thomas William Charles Tolman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Signed and sealed this 2nd day of May 1972.

Dated November 30, 1971 In the Specification:

"RR'NO' -N-O-9RR'N--O-N=O" should be --RR'N0-+ -N--O--RR'N--0--N=O- "3nitronyl" should be -3-nitronyl- "zle" should be -zole- "1. Tobacco" should be --l. A tobacco-- after "lnitronyl" insert -3-oxyl 4,4,5,5-tetramethyl-2-phenyldihydroimidazole;

and l-oxylchange "methyldroimidazole" to -methyldihydroimidaz01e-- (SEAL) Attest:

Attesting Officer ORM PO-IOSO (10-69) ROBERT GOTTSCHALK Commissioner of Patents U5COMM-DC BO375-P59 U 5 GOVERNMENT PRINYING OFFICE I989 O-3G6-334 

2. The filter of claim 1 wherein the said substance is sprayed onto the filtering material as a solution. 